1,2,3,4 Tetrahydrocarbazole-3-carboxylic and 4-carboxylic acids

ABSTRACT

Novel 9-aroyl-1,2,3,4-tetrahydrocarbazoles bearing a carboxy substituent at position 3 or 4 and corresponding esters having antiinflammatory activity, the preparation thereof and novel intermediates therefor are described.

548-621 SR A BEST AvAaLABLE QO XR 3 v 9 9 9 8 J 1'- United S )K f BEST AVAILABLE COPY 1 1 3,9 5,998 Alexander et Sept. 16, 1975 [54] 12,3,4-TETRAHYDROCARBAZOLE-3T 2,075,359 3/1937 Salzberg 5! 8|. 424/250 CARBOXYLIC AND 4-CARBOXYLIC ACIDS OTHER PUBLICATIONS Inventors: i d g z i gg s Heterocyclic Compounds ed. Elderfield, (1952), i ac v01. 3; pages 295-296 QD400 E4.

Bull. Soc. Chim. France, [965 l4ll 1417, Julia et [73] Assignee: Sterling Drug lnc., New York, NY. [22] Filed: Dec. 11, 1972 2 Bull. Soc. Chim. France, 1962 2 2262, Julia et al.

Related U S Application Data J. Chem. Soc. 418 419, (i904), Perkin. [63] ggz' g g 5% Primary Examiner-Sherman D. Winters contiiiuation-in-part of Ser. No: 42,620, June 2, y. Agent, or FirmFrederik W. Stonner; B. 1970, Pat. No. 3,687,969. Woodrow Wyet [52] U.S. CI. 260/315 57 ABSTRACT [5 I] C07D 209/88 [58] Field of Search 260/315 Novel 9-ar0y1;l,lfiA-lelrdhydmcarbazoles bearing a carboxy substltuent at position 3 or 4 and correspond- [56] Reierences Cited ing esters having antiinflammatory activity, the prepa- UNITED STATES PATENTS ration thereof and novel intennedlates therefor are described. l.9l5,334 6/1933 Salzbcrg et al. 260/243 5 Claims, No Drawings l,2,3.4 TETRAHYDROCARBAZOLE-3-CARBOXYLIC AND 4-CARBOXYLIC ACIDS This application is a continuation-in-part of copending application, Ser. No. 200,205, filed Nov. 18, 1971, now U.S. Pat. No. 3,758,496, issued Sept. 11, 1973, in turn a continuation-in-part of Ser. No. 42,620, filed June 2, 1970, now U.S. Pat. No. 3,687,969, issued Aug. 29, 1972.

This invention relates to new tetrahydrocarbazoles and more particularly to a new class ofl,2,3,4- tetrahydrocarbazoles and to processes for their preparation. More specifically this invention relates to 9- carboxylic acyl-l,2,3,4-tet'ahydrocarbazoles bearing at either the 3 or 4 position of the tetrahydrocarbazole ring a carboxy substituent, and corresponding esters.

In one aspect of the invention there are provided compounds having the formula where (A) represents phenyl, naphthyl, 2-thienyl, or cyclohexyl; Q and Q, represent substituents selected from lower-alkyl, phenyl-lower-alkyl, lower-alkoxy, phenyl-lower-alkoxy, phenoxy, phenyl, di(loweralkyllamino, lowcr-alkanoylamino, trihalomethyl, trihalomethoxy, halo ahd hydroxy, where phenyl is unsubstituted or substituted by from one to three of the same or different substituents selected from loweralkyl, lower-alkoxy, trihalomethyl and halo; Z and Z, represent substituents selected from lower-alkylthio, lower-alkylsulfinyl, lower-alkylsulfonyl, amino, and nitro; m represents an integer from 0 to (3-n) inclusive; 0 represents an integer from 0 to (3-g) inclusive; n and g represent integers from O to l inclusive; R represents hydrogen, lower-alkyl, 4-acetamidophenyl, loweralkanoyloxymethyl, benzoyloxymethyl or benzoyloxymethyl substituted on phenyl by from one to two of the same or difi'erent substituents selected from loweralkyl, lower-alkoxy, trihalomethyl, nitro and halo; and R, and R each represent hydrogen or methyl, at least one of which is hydrogen; or (Q),,, taken together with (Z),,, or (0,) taken together with (2,), represent methylenedioxy attached to adjacent carbon atoms.

In another aspect of this invention there are provided compounds having the formula CO R 3,905,998 BEST AVAILABLE COPY wherein (Ar) represents phenyl or naphthyl; Q and 0;, represent substituents selected from lower-alkyl, phenyl-lower-alkyl, lower-alkoxy, phenyl-lower-alkoxy, phenoxy, phenyl, di(lower-alkyl)amino, trihalomethyl, trihalomethoxy, halo and hydroxy, where phenyl is unsubstituted or substituted by from one to three of the same or different substituents selected from loweralkyl, lower-alkoxy, trihalomethyl and halo; Z and 2,, represent loweralkylthio; m represents and integer from 0 to (331 n) Inclusive; p represents an integer from 0 to (3-g) inclusive; n and g represent integers from 0 to l inclusive; R represents hydrogen, loweralkyl, 4-acetamidophenyl, lower-alkanoyloxymethyl, benzoyloxymethyl or benzoyloxymethyl substituted on phenyl by from one to two of the same or different substituents selected from lower-alkyl, lower-alkoxy, trihalomethyl, nitro and halo; and R represents hydrogen or methyl; or (Q m taken together with (2 or (Q taken together with (Z represent methylenedioxy attached to adjacent carbon atoms.

It will be understood, here and throughout the specification, that when R, represents methyl, said methyl can occur at any one of the positions C,, C C or C of the l,2,3,4-tetrahydrocarbazole ring.

The compounds of the invention having formulas l and ll were found to have anti-inflammatory activity when tested in rats according to the pharmacological test procedures more fully described hereinbelow and are indicated for use as anti-inflammatory agents.

As intermediates in one process for the preparation of the compounds of formula I there are provided compounds having the formula COQH 002B (Q),,,. I

wherein (A) represents phenyl, naphthyl, 2-thienyl, or cyclohexyl; Q and Q, represent members of the group consisting of lower-alkyl, phenyl-lower-alkyl, loweralkoxy, phenyl-lower-alkoxy, phenoxy, phenyl, amino. di(lower-alkyl)amino, lower-alkanoylamino, trihalomethyl, trihalomcthoxy, halo and hydroxy; Z and Z, represent members of the group consisting of loweralkylthio, lower-alkylsulfinyl, lower-alkylsulfonyl and nitro; m represents an integer from O to (3-n) inclusive; p represents an integer from 0 to (3-g) inclusive; and n and g represent integers from 0 to l inclusive; or (Q),,, taken together with (Z),,, or (Q,),, taken together with (2,) represent methylenedioxy attached to adjacent carbon atoms.

Compounds of formula ll] where (A) is phenyl or naphthyl are claimed in U.S. Pat. No. 3,687,969.

As intermediates in another process for the preparation of the compounds of formula I there are provided compounds having the formula (A) represents phenyl, naphthyl, Z-thienyl, or cyclohexyl; Q and 0,, represent substituents selected from lower-alkyl, phenyl-lower-alkyl, lower-alkoxy, phenyllower-alkoxy, phenoxy, phenyl, di(lower-alkyl)amino, trihalomethyl, trihalomethoxy and halo, where phenyl is unsubstituted or substituted by from one to three of the same or different substituents selected from loweralkyl, lower-alkoxy, trihalomethyl and halo; Z and Z represent lower-alkylthio', m represents an integer from O to (3-n) inclusive; p represents an integer from O to (3-g) inclusive; n and 3 represent integers from to l inclusive; (Ph) represents phenyl; Q represents a substituent selected from lower-alkyl, lower-alkoxy and halo; r represents an integer from O to 3 inclusive; Z represents hydrogen; and R and R each represent hydrogen or methyl, at least one of which is hydrogen; or (0 taken together with (Z or (Q taken together with (2 or (Q,), taken together with 2,, represent methylenedioxy attached to adjacent carbon atoms.

As intermediates in the preparation of the compound having formula ll there are provided compounds hav- N Z I wherein R represents hydrogen or Ar )--c': o;

BEST AVAILABLE COPY lower-alkylthio; m represents an integer from O to (3n) inclusive; p represents an integer from O to (3- inclusive; n and g represent integers from O to l inclusive; (Ph) represents phenyl; 0,, represents a sub stitucnt selected from lower-alkyl, lower-alltoriy and halo; r represents an integer from O to 3 inclusive; Z represents hydrogen; and R represents hydrogen or methyl; or ((1 taken together with (2 or (Q taken together with (2 or (0,), taken together with Z represent methylenedioxy attached to adjacent carbon atoms.

The compounds having formula IV and formula V are claimed in copending application Ser. No. 200,205, filed Nov. 18, 1971.

It will be understood, here and throughout the specification, that when (A) and (Ar) are naphthyl they are l-naphthyl or Z-naphthyl, and it will be further understood that the substituents represented by Q, Q Q Q1, Z, Z2, Z4 and Z1; Q1 Q3, Q5, Os Z1 Z3, Z5 and n; and Q and Q, can occur at any of the available positions of the benzene ring of the tetrahydrocarbazole; the rings represented by (A) and (Ar); and the ring represented by (Ph) respectfully and where, in each case, there is more than one substituent they can occur in any position combination relative to each other. and, in the case of the substituents represented by Q, to Q inclusive, they can be the same or different.

it will also be understood, here and throughout the specification, that when (Q), taken together with (Z),,; (0,) taken together with (2,) (0 taken together with (2 (Q taken together with (Z (0 taken together with (2 (Q taken together with (2 (Q taken together with Z (Q taken together with (2 (O taken together with (Z and (Q taken together with 2,, represent methylenedioxy attached to adjacent carbon atoms, each such methylenedioxy group can occur at any of the available adjacent positions of the rings represented by (A), (Ar) and (Ph) to which it is attached, and it will be further understood that for any particular compound of the invention, either or both of (0),, taken together with (2),, and (Q,),, taken together with (2,) (formulas l and III), or ((2 taken together with (Z and (Q taken together with (Zulg an (Q9), taken together with Z (formula V) can be methylenedioxy attached to adjacent carbon atoms. (formula IV or (Q,),,, taken together with (21) (Qit),I taken together with (28):: and (Q9)r taken togethfir Z9 (formula V) can be methylenedioxy attached to adjacent carbon atoms.

As used throughout this specification. the terms lower-alkyl, lower-alkoxy, and lower-alkanoyl mean such groups preferably containing from one to six carbon atoms which can be arranged as straight or branched chains, and. without limiting the generality of the foregoing, are illustrated by methyl, ethyl, propyl. isopropyl, butyl. sec-butyl, amyl, hexyl and the like for alkyl; methoxy, ethoxy, propoxy, isobutoxy, hexyloxy and the like for alkoxy; and acetyl, propionyl, butyryl, isobutyryl, hexanoyl and the like for alkanoyl.

As used throughout this specification the term halo means chloro, bromo, iodo and fluoro.

The free acid forms of the compounds of formulas l and II where R and R respectively are hydrogen are convertible to the corresponding salt form by interaction of a particular acid with a base, and such salts are considered to be the full equivalents of the acids and BEST AVAILABLE COPY esters of formulas l and ll. Examples of such salts are salts of heavy metals such as zinc and iron, alkali metal salts, for example, sodium and potassium; alkali earth metal salts, for example, calcium and barium; the aluminum and magnesium salts; and ammonium salts, such as those derived from ammonia or amines such as methylamine, ethylamine, isopropylamine, hexylamine, dimethylamine. diethylamine, methyl ethylarnine, di(- sec-propyl)amine, dihexylarnine, methyl cyclohexylamine, pyrrolidine, piperidine, morpholine, choline, glucosamine, Z-hydroxyethylamine, bis(2-hydroxyethyl)amine, tris( 2-hydroxyethyl)amine and the like. Of course, bu virtue of the herein disclosed pharmaceutical utility of the compounds of formulas l and ll the preferred salts are the pharrnaceutically acceptable salts and such salts are considered to be the full equivalents, particularly for pharmaceutical use, of the free acids and esters of formulas l and II.

In the process aspects of the invention there are provided the processes described more fully hereinbelow as follows:

The compounds of the invention having formula I are prepared by the methods described and illustrated in the flow charts below.

They are prepared by one method by reacting an appropriate l -carboxylic acyl-l-phenylhydrazine (formula Vl) or the corresponding aldehyde l-carboxylic acyl-l-phenylhydrazone, e.g., acetaldehyde or benzaldehyde hydrazone, with an appropriate cyclohexanone-4-carboxylic acid or ester thereof (formula Vll) or the known cyclohexanone-4,4- dicarboxylic acid (formula Vlla) to give the corresponding acid or ester thereof (formula I) or corresponding 1,2,- 3,4,-tetrahydrocarbazole-3,3-dicarboxylic acid (formula lll) respectively and further reacting the dicarboxylic acid (Ill), under pyrolytic conditions, in order to efi'ect mono-decarboxylation to give the corresponding compound of formula 1 (R=H). The condensation reaction is carried out in a suitable solvent, for example acetic acid or, when the corresponding lower-alkyl ester is desired, in an alkanol such as methyl alcohol, ethyl alcohol, isopropyl alcohol or butyl alcohol in the presence of a suitable condensing agent, for example, acids such as hydrochloric, hydrobromic, polyphosphoric, sulfuric and acetic acid, and Lewis acids such as zinc chloride, cuprous chloride, boron trifluoride, boron trifluoride etherate and the like.

VI VI I VIIa l,2,3,4-tetrahydr0carbazole-3-carboxylic 00 R E I 1 N-Nll Q R The reaction of the hydrazines, or corresponding acidaddition salt, having formula V] or corresponding aldehyde l-carboxylic acyl-l-phenylhydrazones with the cyclohexanones having formulas VII and Vlla can be carried out in a suitable solvent at temperatures of from about 20C. to about 125C. for from about 15 minutes to several hours, the choice of solvent, catalyst, temperature and time of reaction depending on the nature of the reactants. If an acid-addition salt of the lcarboxylic acyll -phenylhydrazines is employed, an additional condensing agent is not necessary. Generally, the reaction is conveniently carried out by heating a solution of an appropriate l-carboxylic acyl-lphenylhydrazine of formula VI in the form of its acid addition salt, e.g. hydrochloride salt, and an appropriate cyclohexanone of formula VII or VlIa in glacial acetic acid at about to C. for about 30 minutes. In the case of the aldehyde l-carboxylic acyl-lphenylhydrazones, the reaction is conveniently carried out by heating under reflux a solution of the appropriate benzaldehyde or acetaldehyde l-carboxylic acyl-lphenylhydrazone and an appropriate cyclohexanone of formula Vll (where R=hydrogen or lower-alkyl) or Vlla in glacial acetic acid at from C. to reflux temperature in the presence of an excess of hydrochloric acid or sulfuric acid for l to 6 hours; the acid condensing agent can be added initially or subsequent to the heating of the solution of the reactants until liberation of a stoichiometric amount of aldehyde so formed is complete. The mono-decarboxylation reaction leading to the compounds of formula I where R is hydrogen can be carried out by heating the appropriate dicarboxylic acid having formula Ill, if desired in the presence of a suitable solvent, to a temperature where carbon dioxide evolution begins and continuing heating at about that temperature until carbon dioxide evolution ceases. Generally the reaction proceeds readily when an appropriate dicarboxylic acid of formula lll is heated, in the absence of solvent, at about l70 to 200C.

The compounds of the invention having formula I where R is lower-alkyl can also be prepared from the free carboxylic acids (I, R=H) by standard esterification procedures. In view of the sensitivity to hydrolysis of the 9-carboxylic acyl moiety of the compounds having formula I to the strong acidic conditions used in some procedures to effect esterification, for example. treatment with alkanols in the presence of a strong acid, esterification procedures which avoid such condior loweralkyl) 2 00 1-1 A III tions are preferred, for example. esterification with diazoalkanes or with alkanols (ROH, where R is loweralkyl) in the presence of an equivalent of cyclohexylcarbodiimide. Alternatively the free carboxylic acid (I, R=H) can be slonvcrted to the acid chloride or bromide, using standard procedures, e.g., reaction with thionyl chloride or bromide, followed by treatment with an appropriate alcohol (ROI-I, where R is loweralkyl or 4-acetamidophenyl). The carboxylic acid esters (I, R=alkanoyloxymethyl or unsubstituted or substituted benzoyloxymethyl) are prepared by reacting the free carboxylic acid (I, R=H) with the appropriate chloromethyl alkanoate or an appropriate chloromethyl benzoate in a suitable solvent, e.g., dry dimethylformamide, in the presence of a suitable acid acceptor, e.g., sodium or potassium carbonate or sodium or potassium bicarbonate. The chloromethyl alkanoates and benzoates belong to a well-known class of compounds and are readily prepared by a known procedure, i.e., reaction of the corresponding alkanoic acid chlorides or bromides and benzoic acid chlorides or bromides with paraformaldehyde generally in the presence of a small amount of dry zinc chloride.

The intermediate l-carboxylic acyll phenylhydrazines having formula VI and corresponding aldehyde l-carboxylic acyl-l-phenylhydrazones used in the preparation of the compounds having formulas I and III are known compounds or are readily prepared by standard procedures from the corresponding phenylhydrazines and corresponding carboxylic acyl halides as follows. To a stirred ice-bath cooled solution of acetaldehyde (or other suitable aldehyde, e.g., benzaldehyde) (1.1 mole) in 300 ml. ehter (or other suitable solvent, e.g., methyl alcohol or pyridine) is added slowly the appropriate phenylhydrazine (l mole) and stirring is continued for one hour. The solution is washed with water and the ether layer is separated, dried and evaporated under reduced pressure to give the corresponding acetaldehyde phenylhydrazone which can be purified by standard procedures or used as such in the next step. If pyridine is used as solvent instead of ether, the resulting pyridine solution of the hydrazone is used directly in the next step or is quenched in ice-water and the precipitated hydrazone is collected by filtration. If methyl alcohol is used as solvent, the hydrazone generally precipitates and is collected by filtration. To a stirred ice-bath cooled solution of the thus obtained acetaldehyde phenylhydrazone (0.l2 mole) in 80 ml. of pyridine is added slowly the appropriate carboxylic acyl chloride (slight excess over 0. 12 mole) and the resulting mixture is allowed to warm to room temperature and diluted with ice-water. The resulting corresponding acetaldehyde l-carboxylic acyll -phenylhydrazone, ifa solid, is collected by filtration, washed with water and dried; if a gum or oil, the supernatant liquid is decanted, the residue is dissolved in ether and the solution is washed thoroughly with water, dried and used as such in the next step. Alternatively the acetaldehyde phenylhydrazone is reacted with a slight excess of sodium hydride in dimethylformamide with cooling and the resulting solution of the acetaldehyde phenylhydrazone sodium salt is reacted at room temperature with a slight excess of the appropriate carboxylic acyl chloride for several hours. The mixture is then treated with a sufficient quantity of glacial acetic acid to neutralize excess base and extracted with ether. The ether extract is washed with water, dried, and evaporated to dryness under reduced pressure. The acetaldehyde l-carboxylic acyl-l-phenylhydrazone so BEST AVAILABLE co y obtained is purified using standard techniques or is used as such in the next step. This latter acylation procedure is preferred when the carboxylic acyl chloride and/or the phenylhydrazone bear an ortho substituent. To a stirred solution or suspension of the thus obtained corresponding acetaldehyde l-carboxylic acyl-lphenylhydrazone in ethyl alcohol or in ether is added a solution of hydrogen chloride (in excess of one equivalent) in ether or ethyl alcohol respectively and stirring is continued for I hour. If required, additional ether is then added to aid the precipitation of the resulting corresponding l-carboxylic acyl-l-phenylhydrazine hydrochloride which is collected by filtration and washed with ether and generally is used as such in the next step without further purification. The corresponding free hydrazine can be obtained, if desired, by reaction of the hydrochloride salt with an equivalent amount of appropriate base, using standard procedures.

The phenylhydrazines employed in the preparation of the intermediate compounds having formula VI are known compounds or are readily prepared from the corresponding known anilines, which belong to a well known class of compounds, using standard procedures. For example, a convenient method is the reaction of an appropriately substituted aniline with sodium nitrite in the presence of hydrochloric acid and reduction of the resulting corresponding phenyldiazonium chloride with stannous chloride followed by treatment with sodium hydroxide to give the corresponding substituted phenylhydrazine.

The carboxylic acyl halides employed in the preparation of the intermediate compounds having formula VI are known compounds or are readily prepared from the corresponding known carboxylic acids using standard procedures, e.g., by reaction of an appropriate carboxylic acid with an appropriate halogenating agent such as thionyl chloride or oxalyl chloride.

The intermediate cyclohexanone-4-carboxylic acids having formula VII (R=H) and certain lower-alkyl esters thereof are known compounds. Other lower-alkyl esters thereof can be prepared by standard esterification procedures such as reaction of the carboxylic acid with an appropriate diazoalkane, for example, diazomethane; by reaction of the carboxylic acid with an appropriate alcohol (ROI-I, where R is lower-alkyl) in the presence of an acid catalyst, for example, sulfuric acid or hydrochloric acid, or in the presence of an equivalent of cyclohexylcarbodiimide; and by reaction of the alkali metal salt of the carboxylic acid with thionyl chloride and further reaction of the acid chloride so formed with an appropriate alcohol.

The compounds having formula I are prepared by an alternative method. They are prepared by reacting an appropriate 9-H- l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Iower-alkyl ester (formula VIII) or benzyl ester (formula IV, R =H) with an appropriate carboxylic acyl halide having the formula (IX) below, where X is bromide, chloride or fluoride, to give the corresponding 9-carboxylic acyll ,2, 3 ,4- tetrahydrocarbazole3-carboxylic acid lower-alkyl ester (formula I, R lower-alkyl) or benzyl ester (formula IV,

respectively and further subjecting the benzyl ester so obtained to hydrogenolysis to give the corresponding compound of formula I where R is hydrogen.

EEST AVAILABLE COPY Q 0 5. D H u m 9 1 A)c-x )I (R=l-l N R (z 2 1 (z H 5 8 .33?)

VIII (R lower-alkyl) IX Iv (R5=H) IX Iv The acylation reaction is carried out by converting an appropriate 9-H- l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid ester by known procedures to a suitable salt, for example an alkali metal salt such as the sodium salt (9-Na) and further reacting t. e salt so obtained with an appropriate carboxylic acid halide (lX), in a suitable solvent, at a temperature ranging from about room temperature to about l00C. to give the corresponding compound having formula I (R lower-alkyl) or corresponding compound having formula IV The hydrogenolysis is carried out by subjecting a solution or suspension of the benzyl ester so obtained, in a suitable solvent, to a hydrogen atmosphere at room or elevated temperatures and a pressure of one or more atmospheres in the presence of a suitable catalyst until the required amount of hydrogen has reacted. Suitable solvents that can be used are, for example, methyl alcohol, ethyl alcohol, ethyl acetate or acetic acid and the like. Suitable catalysts that can be used are, for example, nickel, palladium or platinum or such catalysts supported on a suitable medium such as charcoal, e.g., palladium-on-charcoal. The acylation reaction is conveniently carried out by reacting a 9-H-l ,2,3,4- tetrahydrocarbazole-3-carboxylic acid lower-alkyl or benzyl ester with an equivalent of sodium hydride in dimethylformamide at about 60 to lOOC. for about l5 minutes and treating a solution of the sodium salt so ob tained with an equivalent of the carboxylic acyl halide (IX) and continuing heating at about 60 to 100C. for about 1 to 2 hours, and isolating the resulting corresponding 9-carboxylic acyl-1,23,4- tetrahydrocarbazole-3-carboxylic acid lower-alkyl or benzyl ester by standard procedures. The hydrogenolysis of the benzyl ester so obtained is conveniently carried out by suspending or dissolving it in ethyl alcohol and subjecting it to a hydrogen atomsphere in the presence of 5 to 10 percent palladium-on-charcoal, in the amount of about 1 to 5 percent by weight of benzyl ester, at a temperature ranging from room temperature to about 80C., stopping the reaction when about the stoichiometric amount of hydrogen has reacted, and

isolating and purifying the corresponding 3-carboxylic acid by standard procedures.

The compounds having formula I where R is hydrogen are also prepared by subjecting the corresponding t-butyl ester (1, R t-butyl) to pyrolytic conditions which selectively remove the t-butyl moiety to give the corresponding free carboxylic acid. The reaction is conveniently carried out by heating a mixture of the tbutyl ester with powdered porous plate in a nitrogen atmosphere at about 210C.

The carboxylic acyl halides (IX) are known compounds or can be readily prepared from the corresponding carboxylic acids by the known methods described hereinabove.

The intermediate 9-H-l,2,3,4-tetrahydrocarbazole- 3-carboxylic acids lower-alkyl esters (Vlll, R loweralkyl) are prepared by the methods more fully described hereinbelow or are prepared by known esterification procedures from the corresponding 9-H- 1 2,3,4- tetrahydrocarbazole-3-carboxylic acids (Vlll, R=H). For example, an appropriate carboxylic acid can be treated in an alkanol (ROH, where R is lower alkyl) in the presence of hydrogen chloride to give the corresponding ester; or the cyclohexylcarbodiimide method for preparing esters referred to hereinabove may be employed; or an appropriate carboxylic acid can be converted to the alkali metal salt which is then reacted with a halogenating agent to give the corresponding acid halide. The acid halide so obtained is then reacted with an appropriate alcohol (ROl-l, where R is lower alkyl) or its alkali metal salt to give the corresponding ester. A convenient method is reaction of the carboxylic acid with about an equivalent of sodium hydride to give the corresponding sodium salt and further reaction of the salt with thionyl chloride followed by reaction of the carboxylic acid chloride so obtained with the appropriate alcohol or sodium or potassium salt of the alcohol to give the ester (Vlll, R lower-alkyl). The car boxylic esters can also be prepared by the known procedure of reacting the appropriate carboxylic acid with cyclohexylcarbodiimide to give the corresponding symmetrical carboxylic acid anhydride and treating the anhydride so obtained with an appropriate alcohol in the presence of an acid catalyst, for example zinc chloride. The t-butyl esters, intermediates for the pyrolytic conversion to the compounds of formula I (R=H) as described hereinabove. can be conveniently prepared by this latter procedure.

The 9H- l ,2,3,4-tetrahydrocarbazole-3-carboxylic acid benzyl esters (lV, R H) can be prepared from the corresponding frec'carboxylic acids and corresponding known benzyl alcohols using the known esterification procedures described hereinabove. Alternatively, they can be prepared by reacting an alkali metal salt of an appropriate carboxylic acid with an appropriate benzyl bromide or chloride in a suitable solvent. The latter reaction is conveniently carried out by reacting the carboxylic acid with an equivalent of a benzyl chloride and an equivalent of sodium carbonate in dimethylformamide at about 80-l0()C. for about one hour. The benzyl bromides and chlorides belong to a group of well known compounds and are generally known or can be prepared from the corresponding known toluenes by standard halogenation procedures, e.g. reaction of an appropriate toluene with sulfuryl chloride or N- bromosuccinimide in the presence of a peroxide such as benzoyl peroxide to give the corresponding toluenea-chloride or bromide, that is, benzyl chloride or bromide, respectively.

The 9-H-l ,2,3,4-tetrahydrocarbazole-3-carboxylic acids and their corresponding lower-alkyl esters (Vlll) can be prepared from the corresponding phenylhydrazines and cyclohexanone-4-carboxylic acids and its lower-alkyl esters (Vll) using the general procedures described hereinabove for the preparation of the tetrahydrocarbazoles having formula I from the corresponding l-carboxylic acyl-l-phenylhydrazines (Vl) and cyclohexanone-4-carboxylic acids (Vll).

It will be understood that in the methods described hereinabove for the preparation of the compounds of the invention having formula I that, unless otherwise in ica (A), Q, 01 n p g 1 and 2; and Q4. Q5 Q6. 4 5. Z6, 1 8 1. R and R have the same meaning as defined above for formulas l and lll; and formula IV, respectively, except where O and/or Q represents amino or hydroxy.

The compounds of the invention having formulas l and lll where O and/or Q, each includes one or more hydroxy substituents, and/or Z and/or Z each includes an amino substituent, are prepared, if desired, from the corresponding compounds having formulas l and lll where O and/or Q includes one or more benzyloxy substituents, and/or 2 and/or Z includes a nitro substituent, respectively, by well known catalytic hydrogenation procedures whereby said substituents are converted to hydroxy and/or amino substituents. The hy' l l-Z X (R l'ower-alkyl) BEST AVAlLABLE COPY drogenation is carried out at room temperature in an inert solvent, e.g. ethyl alcohol, under essentially neutral conditions in the presence of a suitable catalyst, e.g. Raney nickel or palladium-on-charcoal, at about atmospheric pressure and the hydrogenatior" 'il-S'fDEG' after the stoichiometric amount of hydrogen has reacted.

The compounds of the invention having formula I! are prepared, as illustrated in the flow chart below, from the corresponding 9-H-l 2,3,4- tetrahydrocarbazole-4-carboxylic acid lower-alkyl esters (X, R;, lower-alkyl) and benzyl esters (V, R,,=H) using methods similar to those described hereinabove for the preparation of the compounds having formula l from the 9-H-l,2,3,4-tetrahydrocarbazole-3- carboxylic acid alkyl esters (Vlll, R lower-alkyl) and benzyl esters. (lV, R -H0, that is, by acylation with an appropriate carboxylic acyl halide having the formula Xl below, where X is chloride, bromide or fluoride,

and, in the case of the benzyl esters (Q Ar)-C=O] so obtained, subsequent hydrogenolysis. or in the case of the t-butyl ester (ll, R =t-butyl subsequent pyrolysis, to give the corresponding free carboxylic acid (ll, R,,=H). Since hydroxy substituents will also undergo acylation during this reaction, compounds of the invention where Q represents hydroxy are prepared from corresponding compounds where 0 is benzyloxy, subsequent to the acylation reaction, as more fully disclosed hereinbelow. The carboxylic acyl halides (XI) are knowncompounds or can be prepared by known methods described hereinbefore for the preparation of the carboxylic acyl halides of formula lX.

The compounds of the invention having formula H where R is lower-alkyl, 4-acetamidophenyl, loweralkanoyloxymethyl, benzoyloxymethyl and benzoyloxymethyl substituted as hereinbefore defined can also be prepared from the free carboxylic acids (ll, R =H) by standard esterification procedures as described hereinbefore for the preparation of compounds having formula l (R=lower-alkyl, 4-acetamidophenyl, loweralkanoyloxymethyl, benzoyloxymethyl and benzoylox ymethyl substituted as hereinbefore defined) from the corresponding free carboxylic acids, (1, R=H).

a II (R H. or

lower-allql.)

BEST AVAILABLE COPY ethyl ester (Xlll in a suitable solvent if desired, to give the corresponding intermediate 6-anilinocyclohexanone-2-carboxylic acid ester (XIV) which is then heated with a suitable acid catalyst, e.g. zinc chloride. to effect cyclization to the corresponding 9- henzyl-l ,2,3,4-tetrahydrocarbazole-4-carboxylic acid ester. The ester so obtained is then hydrolyzed, using standard procedures, to the corresponding free 4- carboxylic acid (Xa).

O Me(or E) o mor Et 0 O (Q a, (Q R 7 n benzyl 7 n benzyl XII XIII XIV ZnCl Aydrolysis CO N Xa 7 benzyl preparation of the 9-H-l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid loweralkyl esters (Vlll, R loweralkyl) and benzyl esters (IV, R .,=H) respectively; and in the case where Q, is hydroxy, which substituent is introduced by reductive cleavage of the corresponding compound where Q, is benzyloxy, as described below, such hydroxy substituent is concurrently converted to the corresponding compound where Q, is a benzyloxy substituent. during the preparation of the benzyl ester, or, in the case of the lower-alkyl esters, the hydroxy substituent is converted to a benzyloxy substituent, immediately following the esterification step. The benzyl bromides and chlorides are known compounds or are readily prepared by known halogenating methods from the corresponding toluenes as described hereinabove.

The 9-H- l ,2.3,4-tetrahydrocarbazole-4-carboxylic acids (X, R H) used as intermediates in the preparation of the corresponding lower-alkyl esters (X. R; lower-alkyl) and benzyl esters (V, R.;=H) are prepared from the corresponding 9-benzyl-l ,2,3 ,4- tetrahydrocarbazole-4-carboxylic acids, having the formula Xa below, by reductive removal of the benzyl moiety using known hydrogenolysis procedures, that is,

alkali metal/ammonia chemical reduction, e.g. sodium in liquid ammonia; and in the case where Q is a benzyloxy substituent, the benzyl moiety will concurrently undergo reductive removal to give the corresponding compound where Q, is hydroxy. The Q-benzyl group can be unsubstituted on phenyl or substituted on phenyl. for example, by halo, alkyl. or alkoxy substituents so long as such substitution does not prevent or interfere with the subsequent reductive removal of the 9-bcnzyl group.

The intermediate 9-benzyl compounds having formula Xa are prepared, as illustrated below, by reaction of at least two equivalents of an appropriate phenylbenzylamine (Xll) with one equivalent of an appropriate fi-bromocyclohexanone-2-earhoxylic acid methyl or The reaction is conveniently carried out by mixing together a bromocyclohexanonecarboxylic acid ester (Xlll) and two to two and one-half equivalents of a phenylbenzylamine (X11) and allowing the mixture to stand at from about 20C. to C. for from one-half to 24 hours, depending on the reaction temperature employed, to give the intermediate anilinocyclohexanone (XIV). Depending on the nature of the reactants, the reaction can be performed in the absence of solvent or a suitable solvent such as benzene may be desirable. The intermediate anilinocyclohexanone (XIV) is then heated with zinc chloride at about l00 to 200C. for about one-half to 2 hours and the corresponding 9- benzyll ,2,3,4-tetrahydrocarbazole-4-carboxylic acid ester so obtained is treated with potassium hydroxide in aqueous ethyl or methyl alcohol to give the free carboxylic acid (Xa).

The 6-bromocyclohexanone-2-carboxylic acid esters (Xlll) used as intermediates in the above described procedure are known compounds or can be readily prepared by reacting the corresponding known cyclohexanone-Z-carboxylic acid esters with bromine in a suitable solvent. The reaction is conveniently carried out by treating a cooled solution of the appropriate cyclohexanone-2-carboxylic acid ester in ether or carbon tetrachloride with an equivalent or slight excess of bromine. allowing the solution to stand at room temperature for about l hour. and isolating the resulting o-bromocyclohexanone-Z-carboxylic acid ester by standard techniques.

The intermediate phenylbenzylamines (Xll) are known compounds or are readily prepared by standard procedures from the corresponding known anilines and corresponding known benzaldehydcs as follows. To a stirred warm solution of an appropriate aniline (1.0 mole) in 400 ml. dry methyl alcohol is added dropwise an appropriate benzaldehyde and the solution is heated at reflux for 30 minutes and then cooled on ice. The resulting Schiff base is collected by filtration and washed with methyl alcohol. To a suspension of the latter in methyl alcohol is added portionwise, sodium borohydride 1.0 mole) and the mixture is refluxed about fifteen to thirty minutes after completion of the addition. Water (200 ml.) is added and the mixture is extracted with ether and the ether extract is dried and evaporated to dryness to give the corresponding phenylbenzylamine which is used as such in the next step, or, if desired, is purified by standard procedures before use.

It will be understood that in the methods described hereinabove for the preparation of the compounds of the invention having formula 11 that, unless otherwise indicated, (Ar), (Ph), Q Q 0,, Z Z Z m, n, p, g, r, R R, and R have the same meaning as defined above for formulas II and V respectively. The compounds of the invention having formula 11 where Q, and/or Q each includes one or more hydroxy substituents are prepared, if desired, from the corresponding compounds having formula V where O, and/or Q respectively, includes one or more benzyloxy substituents, by known catalytic hydrogenation procedures as described hereinabove for the preparation of compounds of formula l where O and/or Q includes one or more hydroxy substituents.

The compounds of the invention having formulas I and 11 were found to have antiinflammatory activity as determined by their ability to inhibit asbestos pellet induced granuloma weight increase, carra geenin-induced foot edema and adjuvantinduced arthritis in rats and are useful as antiinflammatory agents.

The following are brief descriptions of the pharmacological test procedures used to determine the above disclosed antiinflammatory activity of the compounds of this invention.

Asbestos Pellet Granuloma Test in Rats Young male rats weighing 100-120 g. are used. Under light ether anesthesia, a single sterilized asbestos pellet weighing approximately 30 mg. is implanted sub cutaneously in the interscapular area via a small skin incision and closed with a wound clip. In any one assay, the pellet weights are within a 2 mg. range. Beginning on the day of pellet implantation, the animals receive 7 daily medications of test compound suspended by triturating in 1% gum tragacanth 'using a ground glass homogenizer and administered by gavage in a volume of 1 ml/lOO g body weight. Control animals receive the vehicle only. Food and water are permitted ad libitum. Twenty-four hours after the last medication, the animals are weighed, sacrificed and the pellets with surrounding granuloma carefully removed and weighed.

Inhibition of Carrageenin-lnduced Foot Edema in Rats Young male rats weighing 100-1 g are used. Food is withdrawn approximately 18 hours prior to medication but the animals are permitted free access to drink ing water up to the time of medication. Drugs to be tested are suspended by triturating in 1% gum tragancanth using ground glass homogenizers and administered by gavage in a volume of 1 ml/ 100 g body weight. Control animals receive the gum tragacanth only. One hour after medication, 0.05 ml of 1% suspension of carrageenin in 0.9% saline is injected into the plantar tissue of the lefet hind paw. Three hours after injection of the carrageenin, edema formation, i.e., increase in foot voluume (difference between left hind paw and the uninjected right hind paw) is measured plethysmographically in the unanesthetized rat.

16 Inhibition Adjuvant-lnduced Arthritis in Rats Adult male rats weighting 200-230 grams are used. Adjuvant (M. butyricum), 0.1 ml of a 0.6% suspension in heavy mineral oil, is injected into the plantar tissue of the left hind paw. A negative control group is injected with mineral oil only. Beginning on the ninth day after adjuvant injection (polyarthritis does not appear until approximately the tenth day after adjuvant administration), the animals receive 6 daily medications of test compound suspended by triturating in 1% gum tragacanth using a ground glass homogenizer and administered by gavage in a volume of l ml/lOO g body weight. Both the negative control and adjuvant injected control animals receive the vehicle only. Food and water are permitted ad libitum. Twenty-four hours after the last medication, the animals are weighed, the degree of arthritic involvement, i.e., increase in foot volume and plasma inflammation units are determined.

Foot volume is measured plethysmographically in the unanesthetized rat.

The compounds of the invention having formulas l and 11 were found to be effective as antiinflammatory agents when administered to rats, as disclosed hereinabove, in the amounts of 40 to mg per kilogram of body weight per dosage unit depending upon the compound used and the condition to be treated. The actual determination of the numerical biological data defini tive for a particular compound is readily determined by standard test procedures by technicians having ordinary skill in pharmacological test procedures, without the need for any extensive experimentation.

The compounds having formulas l and 11 and their pharmaceutically acceptable salts can be prepared for use by conventional pharmaceutical procedures; that is, they can be incorporated in unit dosage form in tablets or capsules for oral administration either alone or in combination with suitable adjuvants such as calcium carbonate, starch, lactose, talc, magnesium stearate, gum acacia, and the like; or as aqueous or oil suspensions or solutions in a pharmaceutically acceptable vehicle such as aqueous alcohol, glycol, oil solutions or oil water emulsions for oral or parenteral administration.

The molecular structures of the compounds of this invention were assigned on the basis of the method of their synthesis and study of their infrared, and in some cases, nuclear magnetic resonance (NMR) spectra, and confirmed by the correspondence between calculated and found values for the elementary analysis for representative examples.

The invention is illustrated by the following examples without, however, being limited thereto.

. EXAMPLE 1 A. 9-Benzoyll ,2,3,4-tetrahydrocarbazole-3-carboxylic acid 9-Benzoyll ,2,3,4-tetrahydrocarbazole-3 ,3-

dicarboxylic acid (3.7 g.) was heated at 200C., till carbon dioxide evolution ceased, to give 2.5 g. of the title compound; m.p. 188-190C. (benzene).

A-l. 9-Benzoyl-l ,2,3,4-tetrahydrocarbazole-3-carboxylic acid (alternative preparation) A suspension of 30 g. of benzaldehyde l-benzoyl-lphenylhydrazcme (m.p. l12-ll4C.) and 14.2 g. of cyclohexanone-4-carboxylic acid in 100 ml. glacial l-Benzoyl-l-phenylhydrazine hydrochloride g.) and 4 g. of cyclohexanone-4,4-dicarboxylic acid in ml. of glacial acetic acid w;re heated at 60-70C. for minutes. The mixture was diluted with water and the resulting solid was collected by filtration and washed with water to give 7.1 g. of the title compound; m.p. 160C. (acetone and hexane).

EXAMPLE 2 A. 9-( 4-Chlorobenzoyl)- i ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 1A but using 3.7 g. of 9-(4-chlorobenzoyl)-l,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid there was obtained 2.5 g. of the title compound; m.p. 2 l 02l 1C. (benzene-hexane B. 9-(4-Chlorobenzoyl l ,2,3,4-tetrahydrocarbazole-3 ,3- dicarboxylic acid Following a procedure similar to that of Example 18 but using 10.7 g. of l-(4-chlorobenzoyl)-lphenylhydrazine hydrochloride and 13 g. of cyclohexanone-4,4-dicarboxylic acid there was obtained crude product, a solution of which in ether was extracted with potassium bicarbonate solution. Acidification of the bicarbonate extract with 10% hydrochloric acid and collection of the resulting solid by filtration yielded 2.7 g. of the title compound; m.p. 2l02l2C. (ethyl acetate-benzene).

EXAMPLE 3 A. 9-Benzoyl-6,7dimethoxy-l ,2,3 ,4-tetrahydrocarbazole- 3-carboxylic acid Following a procedure similar to that of Example 1A but using 5 g. of 9benzoyl-6,7-dimethoxy-l,2,3,4-

tetrahydrocarba2ole-3,3-dicarboxylic acid there was obtained 2.5 g. of the title compound; m.p. l9 l l 94C. (benzene-hexane).

'B. 9-Benzoyl-6,7-dimethoxyl .2,3 ,4-tetrahydrocarbazole- 3,3-dicarboxylic acid Following a procedure similar to that of Example 18 but using 9.3 g. of l-benzoyl-l-(3,4-dimethoxyphenyl) hydrazine hydrochloride (m.p. l50l56C.) and 6 g. of cyclohexanonc-4,4-dicarboxylic acid there was obtained 8 g. crude title compound used directly in the next step; m.p. of purified title compound. 222C. dec. (benzene).

EXAMPLE 4 A. 9-( 4-T0luoyl l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example lA BEST AVAILABLE COPY but using 5 g. of 9-( 4-toluoyl l ,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid there was obtained 3 g. of the title compound; m.p. 2l0-2l2C. (acetone-hexane).

B. 9-( 4-Toluoyl l .2,3,4-tetrahydrocarbazole-3,3- dicarboxylic acid Following a procedure similar to that of Example 1B but using 5.4 g. of l-(4-toluoyl)-l-phenylhydrazine hydrochloride (m.p. 170l76C.) and 4.5 g. of cyclohexanone-4.4-dicarboxylic acid there was obtained 7.2 g. of the title compound; m.p. l-l95C.

EXAMPLE 5 A. 9-(4-Fluorobenzoyl l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 1A but using 4.3 g. of 9-(4-fiuorobenzoyl)-l,2,3,4- tetrahydrocarbazole-3.3-dicarboxylic acid there was obtained 3.2 g. of the title compound; m.p. 180 1 82C. (acetone-hexane).

B. 9(4-Fluorobenzoyl)- l ,2,3,4-tetrahydrocarbazole-3,3-

dicarboxylic acid Following a procedure similar to that of Example 18 but using 5.8 g. of l-(4-fluorobenzoyl)-lphenylhydrazine hydrochloride (m.p. l73l77C.) and 4.5 g. cyclohexanone-4,4-dicarboxylic acid there was obtained 7 g. of the title compound; m.p. l90 lC.

EXAMPLE 6 A. 9-(4-Anisoyl)-l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example lA but using 5.6 g. of 9-(4-anisoyl)-l,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid there was obtained 3.3 g. of the title compound; m.p. l95C.

B. 9-( 4-Anisoyl l ,2,3,4-tetrahydrocarbazole-3,3-

dicarboxylic acid Following a procedure similar to that of Example 18 but using 4.6 g. of l-(4-anisoyl)-l-phenylhydrazine hydrochloride (m.p. l68l70C.) and 3.6 g. of cyclohexanone-4,4-dicarboxylic acid there was obtained 3.3 g. of the title compound; m.p. 205-207C. (benzenehexane).

EXAMPLE 7 A. 9-( 3,4,5-Trimethoxybenzoyl) l ,2,3,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example lA but using the 9-(3,4,5-trimethoxybenzoyl)-l,2.3,4- tetrahydrocarbazole-3,3-dicarboxylic acid obtained in 78 below there was obtained 5 g. of the title compound; m.p. 234-236C.

B. 9-( 3,4,5-Trimethoxybenzoyl 1 ,2,3,4- tetrahydrocarbazole-3.3-dicarboxylic acid Following a procedure similar to that of Example lB BEST AVAILABLE CCPY but using 5.4 g. of l-(3,4,5-trimethoxybenzoyl)-1- phenylhydrazine hydrochloride and 3.6 g. of cyclohexanone-4,4dicarboxylic acid there was obtainedthe title compound; m.p. 208C.

EXAMPLE 8 A. 9-( 3-Toluoyl 1 ,2.3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 1A but using 4.3 g. of 9-(3-toluoyl)-l,-2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid there was obtained 3.2 g. of the title compound; m.p. 180182C.

B. 9-( 3-Toluoyl )-l ,2,3,4'tetrahydrocarbazole-3,3-

dicarboxylic acid Following a procedure similar to that of Example 1B but using 5.6 g. of l-( 3toluoyl)-l-phenylhydrazine hydrochloride (m.p. 170172C.) and 4.5 g. of cyclohexanone-4.4-dicarboxylic acid there was obtained 6.6 g. of the title compound; m.p. l95-200C.

EXAMPLE 9 9-Benzoyl-6-methyll ,2,3 ,4-tetrahydrocarbazole-3- carboxylic acid EXAMPLE 9-(4-Fluorobenzoy1)-6-methyl-1 ,2,3 ,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example 1B but using 15.6 g. of l-(4-fluorobenzoyl)-l-(4-tolyl) hydrazine hydrochloride (m.p. 155C. dec.) and 8.4 g. of cyclohexanone-4-carboxylic acid there was obtained 12.7 g. of the title compound; m.p. 230233C. (acetone-water).

EXAMPLE 1 l 9-[3-(Trifluoromethyl)benzoyl1-1,2,3,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example 1B but using 10 g. of l-[3-(triflouromethyl)benzoyl]-lphenylhydrazine hydrochloride and 5.73 g. of cyclohexanone-4-carboxylic acid there was obtained 8.8 g. of the title compound; m.p. l73-l75C. (etherhexane).

EXAMPLE l2 9-( 4-t-Butylbenzoyl )-1 .2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 19 g. of l-(4-t-butylbenzoyl)-lphenylhydrazine hydrochloride and 10.7 g. of cyclohexanone-4-carboxylic acid there was obtained 13.7 g. of the title compound; m.p. l74-175C. (ace tone-water).

EXAMPLE 13 9-( 3-Bromohenzoyl)- 1 ,2,3.4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 10.7 g. of l-(3-bromo'oenzoyl)-1- phenylhydrazine hydrochloride and 5.35 g. of cyclohexanone-4-carboxylic acid there was obtained 10.2 g. of the title compound; m.p. l186C. (acetone-water).

EXAMPLE 14 9-Benzoyl-6-fluorol ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 1 l g. of l-benzoyl-l-(4-fluorophenyl) hydrazine hydrochloride and 6.87 g. of cyclohexanone-4- carboxylic acid there was obtained 10.5 g. of the title compound; m.p. 218220C. (acetone-water).

EXAMPLE 15 9-( 4-Toluoyl )-6-methyl- 1 ,2,3 ,4-tetrahydrocarbazole- 3-carboxylic acid Following a procedure similar to that of Example 18 but using 3.8 g. of 1-(4-toluoyl)-l-(4-tolyl) hydrazine hydro-chloride (m.p. 273-275C.) and 2.22 g. of cyclohexanone-4-carboxylic acid there was obtained 3 g. of the title compound; m.p. 200203C. (isopropyl alcohol).

EXAMPLE 16 9-( 4-Toluoyl )-6-fluorol ,2,3 ,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 10 g. of 1-(4-toluoyl)-1-(4-fluorophenyl) hydrazine hydrochloride and 5.23 g. of cyclohexanone-4- carboxylic acid there was obtained 9.7 g. of the title compound; m.p. 229-23lC. (acetone-water).

EXAMPLE l7 9-( 4-Fluorobenzoyl )-6-fluoro- 1 ,2,3,4- tetrahydrocarbazole-3-carboxy1ic acid Following a procedure similar to that of Example 15 but using 12.2 g. of l-(4-fluorobenzoyl)-1-(4- fluorophenyl) hydrazine hydrochloride (m.p. C. dec.) and 6.5 g. of cyclohexanone-4-carboxylic acid there was obtained 12.2 g. of the title compound; m.p.

-196C. (acetone-water).

EXAMPLE l8 9-( 4Anisoyl )-6-methyll ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 3.3 g. of l-(4-anisoyl)1-(4-tolyl) hydrazine hydrochloride (m.p. 149l53C.) and 1.91 g. of cyclohexanone-4-carboxylic acid there was obtained 5.1 g. of the title compound; m.p. 172-173C. (isopropyl alcohol).

EXAMPLE l9 9-(4-Anisoyl )-6-fluoro-l ,2,3.4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 14 g. of l-(4-anisoyl)-1-(4-fluorophenyl) hydrazine hydrochloride and 7.03 g. of cyclohexanone-4- carboxylic acid there was obtained 13.5 g. of the title compound; m.p. l97-l98C. (acetone-water).

. methoxyphenyl)hydrazone EXAMPLE 20 9-( 4-Chlorobenzoyl )-6-methoxy- 1 ,2,3,4- tetrahydrocarbazole-3-carboxylic acid rahydrofuran-ether EXAMPLE 2 l 9-Benzoyl-6-methoxyl ,2,3 ,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 13 but using 8.9 g. of l-benzoyl-1-(4-methoxyphenyl) hydrazine hydrochloride and 4.97 g. of cyclohexanone-4- carboxylic acid there was obtained 8.9 g. of thetitle compound; m.p. 2l6-2l9C. (acetone-water).

9-Benzoyl-6-methoxy-l ,2,3 ,4-tetrahydrocarbazole-3- V carboxylic acid (alternative preparation) A solution of 75 g. of benzaldehyde l-benzoyl-l-(4- and 42.6 g. of cyclohexanone-4-carboxylic acid in one liter of acetic acid saturated with hydrogen chloride was heated under reflux for 3 hours during which time hydrogen chloride was continually passed through the solution. The solution was poured into 4 liters of ice-water and the resulting solid was collected by filtration to give 47.4 g. of the title compound; m.p. 2l8-220C. (methyl alcohol).

The benzaldehyde 1-benzoyl-l-(4-methoxyphenyl) hydrazone was prepared as follows: To a solution of 69 g. of 4-methoxyphenylhydrazine in one liter of methyl alcohol was added 53 g. of benzaldehyde and the mixture was heated under reflux for one-half hour. The mixture was cooled to 0C., filtered, and the benzaldehyde 4-methoxyphenylhydrazone (m.p. l26-129C.) was dissolved in 450 ml. pyridine and 63 g. of benzoyl chloride was then added during 5 minutes with stirring and water bath cooling. After one-half hour the reaction mixture was poured into 2 liters of ice-water and the solids were collected by filtration to give 1 19 g. of benzaldehyde l-benzoyll (4-methoxyphenyl )hydrazone; m.p. l5ll53C. (isopropyl alcohol).

EXAMPLE 22 9-( 4-Chlorobenzoyl )-6-methyl- 1 2,3,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example 18 but using 16.5 g. of l-(4-chlorobenzoyl)-l-(4-tolyl) hydrazine hydrochloride and 9.93 g. of cyclohexanone-4- carboxylic acid there was obtained 8.9 g. of the title compound; m.p. 21 l2l4C. (isopropyl alcohol).

EXAMPLE 23 9-( 4-Fluorohenzoyl )-6-mcthoxy- 1 ,2,3,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example lB but using 6.3 g. l-(4-flu0robenzoyl l 4- methoxyphenyl) hydrazine hydrochloride and 2.98 g. of cyclohexanone-4-carboxylic acid there was obtained 3.7 g. of the title compound; m.p. 258260C. (acetone-water BEST AVAILABLE COPY EXAMPLE 24 9-( 4-Toluoyl )-6-methoxyl ,2,3,4-tetrahydrocarbazole- 3-carboxylic acid Following a procedure similar to that of Example 18 but using 5.6 g. of l-( 4-toluoyl)-l-(4-methoxyphenyl) hydrazine hydrochloride and 3.7 g. of cyclohexanone- 4-carboxylic acid there was obtained 7 g. of the title compound; m.p. 257-258C.

EXAMPLE 25 9-( 3-Anisoyl l ,2,3 ,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 1B but using I l g. of l-(3-anisoyl)-l-phenylhydrazine hydrochloride and 6.1 g. of cyclohexanone-4-carboxylic acid there was obtained 1 1.2 g. of the title compound; m.p. l97200C. (acetone-water) EXAMPLE 26 9(4-Ethoxybenzoyl l ,2,3 ,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 18 but using 9 g. of l-(4-ethoxybenzoyl)-lphenylhydrazine hydrochloride and 5 g. of cyclohexanone-4-carboxylic acid there was obtained 5.2 g. of the title compound; m.p. l79-l82C. (acetone-water).

EXAMPLE 27 9-( 3,4-Methylenedioxybenzoyl)- l ,2,3 ,4- tetrahydrocarbazole-3-carboxylic acid Following a procedure similar to that of Example 13 but using 13.6 g. of l-(3,4-methylenedioxybenzoyl)-lphenylhydrazine hydrochloride (m.p. ll C.)

and 6.64 g. of cyclohexanone-4-carboxylic acid there' was obtained 13.4 g. of the title compound; m.p. l 98200C. (acetone-water).

EXAMPLE 28 9-( 3-Chlorobenzoyl )-l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example 1B but using ll.2 g. of l-(3-chlorobenzoyl)-lphenylhydrazine hydrochloride and 6.12 g. of cyclohexanone-4 carboxylic acid there was obtained l l.5 g. ofthe title compound; m.p. l79-l 8 lC. (etherhexane).

EXAMPLE 29 9-( 3-lodobenzoyl l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid Following a procedure similar to that of Example lB but using 21.7 g. of l-(3-iodobcnzoyl)-lphenylhydrazine hydrochloride and 0.5 g. of cyclohexanone-4-carboxylic acid there was obtained l 1.5 g. of the title compound; m.p. 2l0-2l2C. (acetone-water).

EXAMPLE 3O 9-Benzoyl-6-benzyloxyl ,2,3,4-tetrahydrocarbazole-3 carboxylic acid Following a procedure similar to that of Example 18 but using l5.5 g. of l-benzoyl-l-(4-benzyloxyphenyl)- hydrazine hydrochloride and 6.4 g. cyclohexanone-4- carboxylic acid there was obtained l6.3 g. of the title compound; m.p. l93-l94C. (acetone-water).

BEST AVAILABLE COPY Alternatively the 9-benzoyl- 1 ,2,3,4- tetrahydrocarbazole-3-carboxylic acids above (Examples 9 to 30 inclusive) can be prepared following a procedure similar to that of Example 1A but substituting for 9-benzoyl-1.2.3 ,4-tetrahydrocarbazole-3,3- dicarboxylic acid an equivalent amount of the following:

a- 1. 9-benzoyl-6-methyl-12,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

a-2. 9-(4-fluorobenzoyl)-6-methyl-1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-3. 9-[3-(trifluoromethyl)benzoyl] 12,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-4. 9-(4-t-butylbenzoyl l ,2,3,4- tetrahydrocarbazole-3,3dicarboxylic acid;

a-S. 9-(3-bromobenzoyl)-1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-6. 9-benzoyl-6-fluorol ,2,3,4-tetrahydrocarbazole- 3.3-dicarboxylic acid;

a-7. 9-(4-toluoyl)-6-methyl- 1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-S. 9-(4-toluoyl)-6-fluoro-1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-9. 9-( 4-fluorobenzoyl )-6-fluorol ,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

al O. 9-(4-anisoyl)-6-methyl-1,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-l 1. 9-(4-anisoyl)-6-fluoro-l,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a- 1 2. 9-(4-ch1orobenzoyl)-6-methoxy-1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-l 3. 9-benzoyl-6-methoxy-1,2,3 ,4- tetrahydrocarbazole-3,F-dicarboxylic acid;

a-14. 9-( 4-cl lorobenzoyl )6-methyll ,2,3 ,4- tetrahydrocarbazole-3,Z -dicarboxylic acid;

al 5. 9-( 4-fiuo 'obenzoyl)-6-methoxy-1,2,3.4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a- 16. 9 4-t0luoyl)-6-methoxy-1,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

al 7. 9-(3-anisoy1)-1,2,3,4-tetrahydrocarba7Jle-3,3- dicarboxylic acid;

al 8. 9-(4-ethoxybenz0y1 1 ,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-19. 9-( 3,4-methylenedioxybenzoy1)-l ,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-20. 9-( 3-chlorobenzoyl)- 1 ,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid;

a-2l 9-(3-iodobenzoyl)-1,2,3,4-tetrahydrocarbazole- 3,3-dicarboxylic acid; and

21-22. 9-benzoyl-6-benzyloxyl ,2,3 ,4- tetrahydrocarbazole-3,3-dicarboxylic acid. The intermediate 9-benzoyl- 1 2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acids above (a-l to a-22) can be obtained by substituting for cyclohexanone-4-carboxylic acid in Examples 9 to 30 inclusive, equivalent amounts of cyclohexanone-4,4-

dicarboxylic acid.

EXAMPLE 3 1 Ethyl 9-(4-toluoyl)-1,2.3,4-tetrahydrocarbazole-3- carboxylate 1-(4-Toluoyl)-l-phenylhydrazine hydrochloride (13 g.) and 8.7 g. of ethyl cyclohexanone-4-carboxylate (prepared in situ from the corresponding ethylene ketal) in 40 ml. of glacial acetic acid, and ml. glacial acetic acid saturated with hydrogen chloride was warmed on a steam bath for 30 minutes, diluted with water and extracted with ether. The ether extracts were washed with potassium bicarbonate solution and water, dried, and evaporated to dryness. The residue was chromatographed on silica gel using 10% etherpentane as eluant to give 12.7 g. of the title compound; m.p. 72C. (hexane-ether).

EXAMPLE 32 Ethyl 9-benzoyl- 1 ,2,3 ,44etrahydrocarbazole-3-carboxylate Following a procedure similar to that of Example 3 l and using 1 l g. of l-benzoyl-1-phenylhydrazine hydrochloride and 7.62 g. of ethyl cyclohexanone-4- carboxylate (prepared in situ from the corresponding ethylene ketal) there was obtained 6.2 g. of the title compound; m.p. 6769C. (ether pentane).

EXAMPLE 33 9-Benzoyl-2,4-dimethyll ,2,3 ,4-tetrahydrocarbazole- 3-carboxy1ic acid Following a procedure similar to that of Example lB but using 6.5 g. of l-benzoyl-l-phenylhydrazine hydrochloride and 4.6 g. 3,S-dimethylcyclohexanone-4- carboxylic acid and dissolving the resulting solid so obtained in 5 percent potassium bicarbonate solution followed by reprecipitation with dilute hydrochloric acid there was obtained 4.2 g. of the title compound; m.p. l42l 45C. (ether-hexane).

EXAMPLE 34 A. 9-Benzoyl- 1 ,2,3 ,4-tetrahydrocarbazole-4-carboxylic acid A solution of 5.6 g. benzyl 9-benzoyl- 1 ,2,3,4- tetrahydrocarbazole-4-carboxylate in 250 ml. ethyl alcohol containing 0.5 g. 10% palladium-on-charcoal was subjected to a hydrogen atmosphere at 40 p.s.i., while being heated with an infrared lamp and agitated, until uptake of hydrogen ceased. The mixture was filtered, the filtrate was evaporated to dryness under reduced pressure, the resulting residue was dissolved in ether, the ether solution was extracted with dilute potassiur. bicarbonate, the bicarbonate extract was acidified with 3N-hydrochloric acid and extracted with ether and the ether extract was dried and evaporated to dryness. The resulting residue was crystallized from ether-pentane and a solution of the resulting crystals in 5% potassium bicarbonate solution was acidified with 3N hydrochloric acid and the resulting solid was filtered and washed with water to give 1.3 g. of the title compound; m.p. 70-80C.

To an ice cold solution of 28 g. of 9-benzoyl-l ,2,3,4- tetrahydrocarbazole-4-carboxylic acid in ml. dry methyl alcohol was added slowly a solution of 4.55 g. of 87% potassium hydroxide in the minimum required amount of dry methyl alcohol. The solution was diluted to one liter with anhydrous ether and the solid which formed on scratching the side of the reaction flask was collected by filtration. A second crop was obtained on further dilution. There was thus obtained 22 g. of potassium 9-benzoyll ,2,3,4-tetrahydrocarbazole-4- carboxylate; m.p. 254256C. (dec.).

8. Benzyl 9-benzoyll ,2,3,4-tetrahydrocarbazole-4-carboxylate To 0.85 g. sodium hydride in ml. of dry dimethylformamide was added, portionwise, 9 g. of benzyl 1,2,- 3,4-tetrahydrocarbazolel-carboxylate. The mixture was heated on a steam bath for fifteen minutes. the heat BEST AVAILABLE COPY was removed. 4 ml. benzoyl chloride was added dropwise to the still hot mixture and heating was resumed for 2 hours. The mixture, after standing overnight at room temperture, was poured into water containing 4 ml. glacial acetic acid and the resulting mixture was extracted with ether. The ether extract was washed with sodium bicarbonate solution and water, dried and evaporated to dryness. The resulting residue in 50 ml. dimethylformamide was again treated with 0.42 g. sodium hydride and 2ml. benzoyl chloride and worked up as described above and the resulting crude product was chromatograpbed on a 45 mm by 620 mm.'silica gel column using as eluant hexane and hexane containing increasing amounts of ether. There was thus obtained with 7.5% ether in hexane, after evaporation to dryness and recrystallization, 4.6 g. of the title compound; m.p. lO7lO9C. (methyl alcohol).

C. Benzyl l,2,3,4-tetrahydrocarbazole-4-carboxylate A stirred mixture of 13 g. l,2,3,4- tetrahydrocarbazole-4-carboxylic acid, 7.8 g. benzyl chloride and 6.5 g. sodium carbonate in dry dimethylformamide was heated on a steam bath for 1 hour and filtered. The dimethylformamide was evaporated under reduced pressure and the resulting oil was taken up in ether. The ether solution was washed with water, dried and evaporated to give, after recrystallization, 15.5 g. of the title compound, m.p. lO8-l 12C. (heptane).

D. l,2,3,4-Tetrahydrocarbazole-4-carboxylic acid To 40 g. 9-benzyl-l ,2,3,4-tetrahydrocarbazole-4- carboxylic acid in l liter of liquid ammonia was added, with stirring and portionwise, 8.6 g. of sodium. Ammonium chloride was added portionwise until the blue color of the mixture was dissipated. The ammonia was evaporated, water was added and the mixture was extracted with ether. The aqueous solution was chilled and acidified with dilute ydrochloric acid and the resulting solid was collected by filtration and washed with water to give 23 g. of the title compound; m.p. l63l65C. (benzenemethyl alcohol).

E. 9-Benzyll ,2,3,4-tetrahydrocarbazole-4-carboxylic acid A mixture of 53 g. of phenylbenzylamine and 30 g. of ethyl 6-bromocyclohexanone-2-carboxylate was maintained in a nitrogen atmosphere at 35 C. for several days. Fused powdered zinc chloride (48 g.) was added and the mixture was heated at l25-130C. for

1 V2 hours. The cooled mixture was slurried in water and extracted with ether. The ether extract was washed with hydrochloric acid and water, dried, and evaporated to dryness to give 38.5 g. crude ethyl ester of the title compound which was treated with a solution of 48 g. potassium hydroxide in 200 ml. water and 200 ml. ethyl alcohol at reflux temperature for 3 hours. The solution was evaporated to dryness under reduced pressure the resulting residue was dissolved in water and the aqueous solution was extracted with ether and acidified with hydrochloric acid. The resulting solids were collected and dried to give 27.4 g. of the title compound; m.p. 2l2-2l5C. (tetrahyrofuranpentane).

F. Preparation of ethyl o-bromocyclohexanone-2-carboxylate To a stirred solution of 31 g. of ethyl cyclohexanon- 2-carboxylate in ml. of ether. cooled to l0C., was

added dropwise 35 g. of bromine. Stirring was continued 1 hour while the solution was allowed to come to room temperature. The solution was poured into ice water containing 20 g. sodium carbonate and was extracted with ether. The ether extract was washed with water, dried and evaporated to dryness to give 23 g. of the title compound; b.p. 88-9lC. (0.2 mm).

EXAMPLE 35 A. 9-(4-Toluoyl)-1,2,3,4 tetrahydrocarbazole-4- carboxylic acid Following a procedure similar to that of Example 34A but using the crude benzyl 9-(4-toluoyl)-l,2,3,4- tetrahydrocarbazole-4-carboxylate, from Example 35B below, in 250 ml. ethyl acetate and 0.5 g. of 10% palladium-on-charcoal there was obtained 2.6 g. of the title compound; m.p. l8l-l83C. (ether-hexane).

B. Benzyl 9-(4-toluoyl)-1,2,3.4-tetrahydrocarbazole-4- carboxylate To a steam bath warmed mixture of 1.5 g. sodium hydride in 25 ml. of dry dimethylformamide was added, dropwise and with stirring, 9.15 g. of benzyl l,2,3,4- tetrahydrocarbazole-4-carboxylate in 25 ml. dry dimethylformamide followed by 5.4 g. of 4-toluoyl chloride in 15 ml. dry dimethylformamide, and heating was continued for 2 hours. The mixture was cooled and diluted with ether and 1.5 ml. glacial acetic acid. Water was added, the layers were separated and the ether extract was washed with water, 5% potassium bicarbonate solution, 1% aqueous hydrochloric acid and water, and dried over magnesium sulfate. The ether was evaporated to give the title compound which was used without purification in the next step.

EXAMPLE 36 A. 9 -Benzoyl-6-methoxyl ,2,3,4-tetrahydrocarbaz0ne-4- carboxylic acid A solution of 6.7 g. of benzyl 9-benzoyl-6-methoxyl,2,3,4-tetrahydrocarbazole-4-carboxylate in 250 ml. of ethyl acetate was hydrogenated over I g. palladiumon-charcoal until the required amount of hydrogen had reacted. The mixture was filtered and the filtrate was evaporated to dryness under reduced pressure. The residue was slurried in ether and the resulting solid was collected by filtration to give 1.8 g. of the title compound; m.p. l57l59C.

B. Benzyl 9-benzoyl-6-methoxy- 1,2,3 ,4-tetrahydrocarbazole-4- carboxylate Following a procedure similar to that of Example 358 but using 0.67 g. sodium hydride, 37 ml. of dry dimethylformamide, 7.5 g. of benzyl 6-methoxy-l,2,3,4- tetrahydrocarbazole-4-carboxylate, and 2.9 ml. benzoyl chloride there was obtained l0..6 g. of residue which was triturated in hot hexane to give 6.7 g. of the title compound which was used without further purification in the next step.

C. Benzyl 6-methoxyl ,2,3 ,4-tetrahydrocarbazole-4-carboxylate Following a procedure similar to that of Example 34C but using 37.2 g. of 6-meth0xy-l.2.3,4-

tetrahydrocarbazole-4-carboxylic acid, 19.5 g. of benzyl chloride and 16.8 g. of sodium carbonate in 300 ml. of dry dimethylformamide there was obtained 40.3 g. of the title compound; m.p. 8l83C. (ethyl alcoholpentane D. 6-Methoxyl ,2,3 ,4-tetrahydrocarbazole-4-carboxy1ic acid Following a procedure similar to that of Example 34D but using 32 g. 9-benzy1-6-methoxy-1,2,31,4- tetrahydrocarbazo1e-4-carboxylic acid, 500 ml. of liquid ammonia and g. of sodium there was obtained 7.7 g. of the title compound; m.p. 175-177C. (tetrahydrofuran-hexane). Alternatively the title compound can be prepared by substituting an equivalent amount of 9-(4-chlorobenzyl)-6-methoxy-1,2,3 ,4- tetrahydrocarbazole-4-carboxy1ic acid for the 9-benzy1 compound in this procedure.

E. 9-Benzyl-6-methoxy- 1 ,2,3,4-tetrahydrocarbazole-4- carboxylic acid EXAMPLE 37 A. 9-( 4-Ch1orobenzoyll ,2,3 ,4-tetrahydrocarbazole-4- carboxylic acid Following a procedure similar to that of Example 36A but using 4.6 g. benzyl 9-(4chlorobenzoyl)- l,2,3,4-tetrahydrocarbazole-4-carboxylate in 250 ml. of ethyl acetate and 1 g. 10% palladium-on-charcoal there was obtained the title compound which, without further purification, was treated according to the procedure of Example 34A with 0.64 g. of 87% potassium hydroxide in 40 ml. methyl alcohol to give 3 g. ofpotassium 9-(4-chlorobenzoyl)-l,2.3,4- tetrahydrocarbazole-4-carboxy1ate; m.p. 244247C.

B. Benzyl 9-( 4-chlorobenzoyl )-1 ,2,3,4-tetrahydrocarbazole-4- carboxylate Following a procedure similar to that of Example 358 but using 0.8 g. sodium hyride, 90 ml. dimethylformamide, 9.15 g. of benzyl l,2,3,4- tetrahydrocarbazole-4-carboxylate and 5.4 g. of 4- chlorobenzoylchloride there was obtained 6.2 g. of the title compound; m.p. l23124C. (ethyl alcohol).

EXAMPLE 38 A. 9-( 4-Chlorobenzoyl )-6-methoxy- 1 ,2,3 ,4- tetrahydrocarbazole-4-carboxylic acid Following a procedure similar to that of Example (4-methoxyphenyl asst AVAILABLE COPY 36A but using 11 g. of benzyl 9-(4-ch1orobenzoyU-6- methoxyl ,2,3 ,4-tetrahydrocarbazole-4-carboxylate, from Example 388 below, in 250 ml. ethyl acetate and 1 g. of palladium-on-charcoal there was obtained 5.6 g. of the title compound; mpv l8l-185i1 then.

B. Benzyl 9-(4-ch1orobenzoyl) A-methoxy1,2,3,4-

tetrahydrocarbazole-4-carboxy1ate Following a procedure similar to that of Example 35B but using 0.85 g. sodium hydride, 50 ml. of dry dimethylformamide, 10 g. of benzyl 6 -methoxy-1,2,3,4- tetrahydrocarbazole-4-carboxylate, and 5.8 g. of 4- chlorobenzoyl chloride there was obtained 1 1 g. of the title compound which was used without purification in the next step.

EXAMPLE 39 A. 9-Benzoy1-6-methyl- 1 ,2,3,4-tetrahydrocarbazo1e-4- carboxyliic acid Following a procedure similar to that of Example 36A but using 5.9 g. of benzyl 9-benzoyl-6-methy1- l,2,3,4-tetrahydrocarbazo1e-4-carboxylate in 250 ml. ethyl acetate and l g. of palladium-on-charcoal there was obtained 4 g. of the title compound; m.p. 149 1 5 3C. (ether-n-hexane).

B. Benzyl 9-benzoyl-6-methyl-1,2,3 ,4-tetrahydrocarbazole-4- carboxylate Following a procedure similar to that of Example 358 but using 0.84 g. sodium hydride, 50 ml. of dry dimethylformamide, 9.1 g. of benzyl 6-methyl-1.2,3,4- tetrahydrocarbazo1e-4-carboxylate, and 4.4 g. of benzoyl chloride, but eliminating the 1% aqueous hydrochloric acid wash subsequent to the bicarbonate wash, there was obtained 8.5 g. of the title compound which was purified by suspension in hot isopropyl alcohol, filtration, followed by suspension in, and filtration from, ether; m.p. 119121C.

C. Benzyl 6-methyl-1,2,3 ,4-tetrahydrocarbazo1e-4-carboxylate Following a procedure similar to that of 34C but using 8.2 g. of 6-methyl-1,2,3,4-tetrahydrocarbazole-4- carboxylic acid, 4.6 g. of benzyl chloride and 4 g. of sodium carbonate in 50 ml. dry dimethylformamide there was obtained 9.1 g. of the title compound; m.p. 1 15l 17C. (ethyl alcohol-pentane).

D. 6-Methy1-1,2,3,4-tetrahydrocarbazo1e-4-carboxy1ic acid Following a procedure similar to that of Example 34D but using 27.5 g. of 9-benzyl-6-methyl-l2.3.4- tetrahydrocarbazo1e-4-carboxylic acid, 500 ml. of liquid ammonia and 5.9 g. of sodium there was obtained 12.2 g. of the title compound; m.p. 194i97C. (acetone-water).

E. 9-Benzyl-6-methyl-1,2,3,4 tetrahydrocarbazole-4- carboxylic acid Following a procedure similar to that of Example 34E but using 57 g. of (4-t0lyl)-benzy1amine, 30 g. of ethyl 6-bromocyclohexanone-Z-carboxylate and 48 g. of fused powdered zinc chloride; and 20 g. of potassium hydroxide in aqueous ethyl alcohol, there was obtained 33 g. of the title compound; m.p. 200-208C. (acetone-water) which on recrystallization from acetonebenzene had m.p. 2022 C.

Following a procedure similar to that of Example 31 but substituting in each case for l-(4-toluoyl)-lphenylhydrazine hydrochloride an equivalent amount of l-benzoyl-l-phenylhydrazine hydrochloride and for ethyl cyclohexanone-4-carboxylate an equivalent amount of the following:

methyl cyclohexanone-4-carboxylate;

t-butyl cyclohexanone-4-carboxylate; and

hexyl cyclohexanone-4-carboxylate; there can be obtained respectively bl methyl 9-benzoyl-l ,2,3,4-tetrahydrocarbazole- 3-carboxylate;

b-2. t butyl 9-benzoyl-l ,2,3,4-tetrahydrocarbazole-3- carboxylate; and

b-3. hexyl 9-benzoyll ,2,3,4-tetrahydrocarbazole-3- carboxylate. The intermediate cyclohexanone-4-carboxylates above can be prepared from the corresponding free acids respectively using the standard esterification procedures disclosed hereinabove.

The title compound of Example 1A can alternatively be obtained from the corresponding t-butyl ester (b-Z) above by pyrolysis according to the general procedure disclosed hereinabove.

Following a procedure similar to that of Example 13 but substituting in each case for cyclohexanone-4,4- dicarboxylic acid in an equivalent amount of cyclohexanone-4-carboxylic acid and for lbenzoyl-lphenylhydrazine hydrochloride an equivalent amount of the hydrochlorides of the following:

l-( naphthoyl)- l -phenylhydrazine;

l-( Z-naphthoyl l -phenylhydrazine;

l-( 4-chlorol -naphthoyl l-( 4-methoxyphenyl)hydrazine;

l-( 6-bromo-2-naphthoyl)- l-( 4-chlorophenyl )hydrazine;

l-( 4-fluorol -naphthoyl l 4-methoxyphenyl )hydrazine;

l-( 4-methoxyl -naphthoyl l -phenylhdyrazine; l-( 4-dimethylaminol -naphthoyl lphenylhydrazine; and l-( 4,8-dimethoxy-3-methyl-2-naphthoyl l phenylhydrazine; there can be obtained respectively cl. 9-( l-naphthoyl l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid; v c-2. 9-( Z-naphthoyl )-l ,2,3,4-tetrahydrocarbazole-3- carboxylic acid; 0-3. 9-( 4-chlorol -naphthoyl )-6-methoxyl ,2,3 ,4-

tetrahydrocarbazole-3-carboxylic acid; c-4. 9-( 6-bromo-2-naphthoyl )-6-chloro- 1 ,2,3,4-

tetrahyrocarbazole-3-carboxylic acid; c-5. 9-( 4-fluorol -naphthoyl )-6-methoxyl ,2,3 ,4-

tetrahydrocarbazole-B-carboyxlic acid; c-6. 9-(4-methoxy-l-naphthoyl)-l,2,3,4

tetrahydrocarbazole-3-carboxylic acid; c-7. 9-( 4-dimethylaminol -naphthoyl 1 ,2,3 ,4-

tetrahydrocarbazole-3-carboxylic acid; and c-8. 9-( 4,8-dimethoxy-3-methyl-2-naphthoyl l,2,3,4-tetrahydrocarbazole-3-carboxylic acid. The intermediate l-naphthoyl-l-phenylhydrazine hydrochlorides above can be prepared from the corresponding naphthoyl chlorides and phenylhydrazines respectively following the general procedure disclosed hereinabove. The naphthoyl chlorides can be obtained BEST AVAILABLE COPY from the corresponding known naphthoic acids using the standard procedure disclosed hereinabove.

Alternatively the Q-naphthoyll ,2,3 ,4- tetrahydrocarbazole-3-carboxylic acids above (c-l to c-8) can be obtained by pyrolytic decarboxylation using a procedure similar to that of Example LA but substituting for 9-benzoyll ,2,3,4-tetrahydrocarba2ole- 3,3-dicarboxylic acid an equivalent amount respectively of the following:

dl 9-( l -naphthoyl)- l ,2,3,4-tetrahydrocarbazole- 3,3-di carboxylic acid; d-2. 9-( 2-naphthoyl)- l ,2,3,4-tetiahydrocarbazole- 3,3-dicarboxylic acid; d-3. 9-(4-chlorol-naphthoyl)-6-methoxyl ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; d-4. 9-( 6-bromo-2-naphthoyl )-6-chloro-l ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; d-5. 9-( 4-fluorol-naphthoyl )-6-methoxy- 1 ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; d-6. 9-(4-methoxyl -naphthoyl)- l ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; d-7. 9-( 4-dimethylaminol-naphthoyl)- l ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; and d-8. 9-(4,8-dimethoxyQ-methyl-Z-naphthoyl)- l ,2,3,4-tetrahydrocarbazole-3 ,3-dicarboxylic acid. The above intermediate 3,3-dicarboxylic acids (d-l to d-8) can be prepared by following a procedure to that of Example 18 but substituting for l-benzoyl-lphenylhydrazine hydrochloride an equivalent amount respectively of the hydrochlorides of the corresponding l-naphthoyl-l-phenylhydrazines listed above as intermediates in the preparation of compounds c-l to c-8. Following a procedure similar to that of Example 18 but substituting in each case for cyclohexanone-4,4- dicarboxylic acid an equivalent amount of cyclohexanone-4-carboxylic acid and for l-benzoyl-lphenylhydrazine hydrochloride an equivalent amount of the hydrochlorides of the following:

l-( 4-trichloromethoxybenzoyl l 4-hexylphenyl hydrazine; l-(4-hexyloxybenzoyl l 4-t-butylphenyl )hydrazine; l 4-phenoxybenzoyl)- l 3-chloro-4-hexylthiophenyl )hydrazine; l-( 4-hexylbenzoyll 3,5-dibromophenyl )hydrazine; l-(4-phenylbenzoyl)-l-(4-iodophenyl)hydrazine; l -[4-(4-phenylbutoxy)benzoyl1- l-[4- (trifluoromethoxy )-phenyl lhydrazine; l-( 3,5-dibromo-4-butoxybenzoyl l 3 ,4-

methylenedioxyphenyl)hydrazine; l-[2-( 3-phenylpropyl )benzoyl1- l -phenylhydrazine; l-[4-(Z-phenylpropyl)benzoyll-l-(4-isopropylthiophenyl)hydrazine; l-[ 4-( dimethylamino )benzoyl l 4-isopentyloxyphenyl )hydrazine; l-( methylthiobenzoyl l-( 4-benzylphenyl )hydrazine; l-( 4-isopropylthiobenzoyl l-( 2-chloro-4-hexyloxyphenyl )hydrazine; l-( Z-hexylthiobenzoyl l -[3-(5-phenylpentyl)- phenyl l-hydrazine; l-[4-( dibutylamino )benzoylll 3-fluorophenyl )hydrazine; l-benzoyll-[4-( diethylamino)phenyl lhydrazine; l-benzoyll -[4-( dimethylamino)phenyllhydrazine; l-[ 3-( trifluoromethoxy )benzoyl l 4-acetarnidophenyl )hydrazine;

f-7. 9-(3,5-dibromo-4-butoxybenzoyl)-6,7- methylenedioxyl ,2,3 ,4-tetrahydrocarbazole-3 ,3- dicarboxylic acid;

f-S. 9-[2-(3-phenylpropyl)benzoyll]-1,2,3 ,4-

tetrahydrocarbazzole-3,3-dicarboxylic acid;

f-9. 9- 4-( 2-phenylpropyl )benzoyl -isopropylthiol,2,3,4-tetrahydrocarbazole-3,3-dicarboxylic acid;

fl O. 9-[4-(dimethylamino)benzoyl ]-6-isopentyloxyl,2,3,4-tetrahydrocarbazole-3,3-dicarboxylic acid;

f-l l 9-(4-methylthiobenzoyl )-6-benzyll ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

fl 2. 9-( 4-isopropylthiobenzoyl )-8-chloro-6- hexyloxyl ,2,3 ,4-tetrahydrocarbazole-3,3- dicarboxylic acid;

fl 3. 9-( 2-hexylthiobenzoyl )-5-( 5-phenylpentyl)- l ,2,3,4-tetrahydrocarbazole-3,3-dicarboxylic acid;

f-14. 9-[4-(dibutylamino)benzoyl]-5-fluoro-l,2,3,4-

tetrahydrocarbazole-3,3-dicarboxyiic acid;

f-l 5. 9-benzoyl-6-(diethylamino)-1,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

fl 6. 9-benzoyl-6-( dimethylamino)- 1 ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-] 7. 9-[ 3-( trifluoromethoxy )benzoyl]-6acetamido 1,2,3,4-tetrahydrocarbazole-3,3-dicarboxylic acid;

fl 8. 9-benzoyl-7-methoxy-6-( -phenylhexyloxy l ,2,3,4-tetrahydrocarbazole-3,3-dicarboxylic acid;

fl 9. 9-( 3-t-butylsulfinylbenzoyl )-l ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-20. 9-( 3-t-butylsulfonylbenzoyl )-8-phenyll ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-2 l 9-(4-acetamidobenzoyl )-8-phenoxy-l ,2,3 ,4-

tetrahydrocarbazole-3,S-dicarboxylic acid;

f-22. 9-(4-butyramidobenzoyl)-6-methylthio-1,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-23. 9-benzoyl--methylsulfonyl-1 ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-24. 9-benzoyl-6-hexylsulfonyll ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-25. 9-benzeyl-4-iobutylsulfonyll ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-26. 9-benzoyl-7-t-butylsulfinyl- 1 ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-27. 9-benzoyl-6-methylsulfinyl-l ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-28. 9-benzoyl-6-( trifluoromethyl 1 ,2,3,4-

tetrahydrocarbazole3,3-dicarboxylic acid;

f-29. 9-benzoyl-6-( trichloromethyl )-l ,2,3,4-

tetrahydrocarbazole3,3-dicarboxylic acid;

f-30. 9-(4-benzyloxybenzoyl)-1,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

f-3 l. 9-(4-nitrobenzoyl)-1,2,13,4- tetrahydrocarbazole-3,3-dicarboxylic acid; and

f-32. 9-benzoyl-6-nitrol ,2,3,4-tetrahydrocarbazole- 3,3-dicarboxylic acid.

The above intermediates 3,3-dicarboxylic acids (f-l to f-32) can be prepared by following a procedure similar to that of Example lB but substituting for l-benzoyllphenylhydrazine hydrochloride an equivalent amount respectively of the hydrochlorides of the corresponding l-benzoyl-l-phenylhydrazines listed above as intermediates for the preparation of compounds e-l to e-32 inclusive. The intermediate l-benzoyll -phenylhydrazine hydrochlorides listed above can be prepared from the corresponding benzoyl chlorides and corresponding phenylhydrazine using the general procedure disclosed hereinabove. The intermediate benzoyl chlorides and intermediate phenylhydrazines, listed above as inter- BEST AVAlLABLE COPY mediates in the preparation of compounds e-] to e-4O inclusive, are known compounds or can be prepared from the corresponding known benzoic acids and corresponding known anilines respectively using the general procedures disclosed hereinabove.

By using the general procedure described hereinbefore for the hydrogenation of benzyloxy and nitro substituents to hydroxy and amino substituents respectively there can be obtained from 9-benzoyl-6- benzoyloxyl ,2,3 ,4-tetrahydrocarbazole-3 -carboxylic acid (Example 30), compounds e-30 to e-32 inclusive above, 9-benzoyl-6-benzyloxy- 1 ,2,3,4- tetrahydrocarbazole-3,3-dicarboxylic acid (a-22) and compounds f-30 to f-32 inclusive above respectively the following:

gl 9-benzoyl-6-hydroxy- 1 ,2,3,4-

tetrahydrocarbazole-3-carboxylic acid;

g-2. 9-( 4-hydroxybenzoyl )-1 ,2,3,4-

tetrahydrocarbazole-3-carboxylic' acid;

g-3. 9-(4-aminobenzoyl)- 1 ,2,3,4-

tetrahydrocarbazole-3-carboxylic acid;

g-4. 9-benzoyl-6-aminol ,2,3 ,4-tetrahydrocarbazole- 3-carboxylic acid;

g-5. 9-benzoyl-6-hydroxyl ,2,3 ,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

g-6. 9-( 4-hydroxybenzoyl 1 ,2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid;

g-7. 9-(4-aminobenzoyl 1 .2,3,4-

tetrahydrocarbazole-3,3-dicarboxylic acid; and

g-S. 9-benzoyl-6-aminol ,2,3 ,4-tetrahydrocarbazole- 3,3-dicarboxylic acid.

The 3,3-dicarboxylic acids above (g-S to g-8) can be converted to the corresponding 3-carboxylic acids (g-l to g-4above) by pyroiytic decarboxylation according to a procedure similar to that of Example IA.

Alternatively, as described hereinabove, the 9- benzoyll ,2,3,4-tetrahydrocarbazole-3-carboxylic acids can be prepared from their corresponding benzyl esters. Thus, by following a procedure similar to that of Example 34A but substituting for benzyl 9-benzoyll,2,3,4-tetrahydrocarbazole-4-carboxylate an equivalent amount of the following:

h- 1. benzyl 9-benzoyl-8-phenyll ,2,3 ,4-

tetrahydrocarbazole-3-carboxylate; and h-2. benzyl 9-benzoyl-6-benzyloxy-l ,2,3,4-

tetrahydrocarbazole-S-carboxylate there can be obtained respectively il 9-benzoyl-8-phenyll ,2,3,4-tetrahydrocarbazole- 3-carboxylic acid; and i-2. 9-benzoyl-6-hydroxy- 1 ,2,3,4-

tetrahydrocarbazole-3-carboxylic acid. The intermediate benzyl esters h-l and h-2 above can be prepared by following a procedure similar to that of Example 358 but substituting in each case for 4-toluoyl chloride an equivalent amount of benzoyl chloride and for benzyl l,2,3,4-tetrahydrocarbazole-4-carboxylate an equivalent amount respectively of the following:

j-l benzyl 8-phenyll ,2,3,4-tetrahydrocarbazole-3- carboxylate; and j-2. benzyl -benzoyloxy- 1 2,3,4-

tetrahydrocarbazole-B-carboxylate. The intermediate benzyl esters j-l and j-2 above can be prepared following a procedure similar to that of Example 34C but substituting for 1.2.3.4- tetrahydrocarbazole-4-carboxylic acid an equivalent amount respectively of the following: 

1. 6-BENZYLOXY-1,2,3,4-TETRAHYDROCARBAZOLE-3-CARBOXYLIC ACID.
 2. 8-Phenyl-1,2,3,4-tetrahydrocarbazole-3-carboxylic acid.
 3. 9-(4-Chlorobenzyl)-6-methoxy-1,2,3,4-tetrahydrocarbazole-4-carboxylic acid.
 4. 9-Benzyl-6-methyl-1,2,3,4-tetrahydrocarbazole-4-carboxylic acid.
 5. 6-Methyl-1,2,3,4-tetrahydrocarbazole-4-carboxylic acid. 